Antibiotics such as virginiamycin are used in the treatment of fermentative acidosis and side effects thereof in sheep, cattle and horses and in the management of necrotic enteritis in poultry. There are however problems associated with their use, such as a reduction in feed intake or loss of appetite upon introduction of the antibiotic into the diet. Reduced feed intake leads to loss of weight and less efficient feed conversion in production animals, and can affect athletic performance in performance horses. A sudden decrease in feed intake and reduced rate of digesta flow can lead to mild constipation and create conditions suitable for bacterial proliferation in the digestive tract.
It is known that when virginiamycin is first included in the diets of sheep, cattle and horses feed intake reduces to levels significantly below pre-treatment control levels for between 2 to 4 days before returning to normal. The use of very high concentrations of virginiamycin (500 mg/kg complete feed) has been shown to reduce feed intake in horses before returning to normal. The reason for this reduced feed intake is not known and it is apparent that it is not simply a question of taste and therefore a problem that can be overcome through modifying feed formulation.
Currently there is no known method for overcoming the reduction in feed intake in animals resulting from introduction of antibiotics into the diet. There is therefore a need for a method of preventing a reduction in feed intake in animals, wherein the reduction results from the introduction of antibiotics into the diet. There is also a need for treatments of diseases and conditions using antibiotics wherein the commencement of the treatment regime does not result in a reduction in feed intake.
The present invention is based on the surprising discovery by the inventors that administering increasing doses of antibiotics over a specified time period substantially prevents a reduction in feed intake.